Career Advice About Lucid Software

I recently joined a Big Tech company. My assigned mentor is helpful when I have questions, and is also friendly.

However, apart from asking questions when I get stuck, I'm not sure how to best use their time so I can onboard and grow effectively. Does anyone have some suggestions and insight on this?

I've considered asking them to explain how some parts of the codebase work when I have issues, but it feels like unless I work on those parts of the codebase, I will forget what I learn. The domain and codebase is large so this feels low-ROI, especially since I am not working on some of these pieces.

I'm currently working as an SRE (Site Reliability Engineer). I was, and am still interested in being a Software Engineer.

I am interested in switching in the future to a normal software engineering role, but want to make the most of my current situation since I recently joined the company (late-stage startup).

What do you think would be some good skills, exposure, things I could learn as an SRE that would be useful to a Software Engineer?

If I'm interested in exploring a new area in my company, say I want to do back end development and I'm currently an SRE, but I don't have any real experience in backend development, do you have some suggestions on how I can explore this and possibly switch over to being a backend engineer?

Like, if I wanted to take on new tasks in backend, for instance - how would I go about identifying opportunities and/or tasks in that area if I don't have such tasks in my current team?